/**
   http://oj.noi.cn/oj/#main/show/1006
 */
#include<stdio.h> 
int main()
{
	int a = 0;
	int b = 0;
	int c = 0;
	scanf("%d %d %d", &a, &b, &c);
	int d = 20 - a - b - c;
	printf("%d", d);
	return 0;
}
